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971.
Yuki Uohashi Koichi Suzumori Hironari Taniguchi 《Journal of Mechanical Science and Technology》2010,24(1):219-222
In recent years, research and development on micro fluid systems has become active in the fields of chemical technology and biotechnology. For the realization of these micro fluid systems, micro fluid devices such as micro-valves and micro pumps are very important. This paper reports the fabrication and experimental evaluation of several micro one-way valves. The valves are fabricated through a micro molding process, which makes the fabrication process simple and suitable for mass production. The experimental results indicate that the developed valve has great performance with a normal flow rate of 130.2 ml/min and a leak flow of 2.2 ml/min. The normal flow rate is 1.4 times higher than that of the previous model. 相似文献
972.
Bo Wang Shao-Chun Xu Feng Jin Jian-Feng Yang Kozo Ishizaki Koichi Niihara 《Ceramics International》2014
Near zero thermal expansion porous ceramics were fabricated by using SiC and LiAlSiO4 as positive and negative thermal expansion materials, respectively, bonded by glassy material. The microstructure, mechanical properties, and thermal expansion behavior of LAS/SiC porous ceramics with different particle sizes of LiAlSiO4 were investigated. The results indicated that the coefficient of thermal expansion of the LAS/SiC porous ceramics decreased from 0.5206×10−6 to −1.1053×10−6 K−1 with increasing the LiAlSiO4 particle size from ~45 µm to ~125 μm. It was attributed to the reduction in the reaction between LiAlSiO4 and SiO2 as the particle size of LiAlSiO4 increased. Young’s modulus increased from 36 MPa to 54 MPa as the sintering temperature increased from 850 °C to 950 °C because of the good bonding between the SiC grains and the glass materials. 相似文献
973.
提出一种主要由伺服电机、径向磁化盘状永磁铁、"F"形导磁体及悬浮物构成的可控磁路式并联型永磁悬浮系统。系统中,并联悬浮物是置于导磁体正下方两个不同重量的铁球,伺服电机驱动盘状永磁铁旋转,改变通过悬浮物的有效磁通量,进而控制悬浮力大小,实现两铁球的稳定悬浮。根据系统结构及可控磁路式并联型永磁悬浮原理将系统模型简化,并建立系统的数学模型,分析使系统稳定悬浮的可能性,计算使系统稳定悬浮的PD控制器反馈增益范围。实验结果表明:在控制器参数满足计算范围条件下,当给系统一较小阶跃外扰时,在实时控制系统作用下,系统在很短的响应时间内可达到新的稳定悬浮状态;相同的外扰可导致左右球异向的位移响应结果,左球移动方向与外扰相同,而右球相反。 相似文献
974.
Takeda S Nakamura M Ishii A Subagyo A Hosoi H Sueoka K Mukasa K 《Nanoscale research letters》2007,2(4):207-212
We fabricated a pH-sensitive device on a glass substrate based on properties of carbon nanotubes. Nanotubes were immobilized
specifically on chemically modified areas on a substrate followed by deposition of metallic source and drain electrodes on
the area. Some nanotubes connected the source and drain electrodes. A top gate electrode was fabricated on an insulating layer
of silane coupling agent on the nanotube. The device showed properties of an n-type field effect transistor when a potential was applied to the nanotube from the top gate electrode. Before fabrication
of the insulating layer, the device showed that the p-type field effect transistor and the current through the source and drain electrodes depend on the buffer pH. The current
increases with decreasing pH of the CNT solution. This device, which can detect pH, is applicable for use as a biosensor through
modification of the CNT surface. 相似文献
975.
We show several pieces of Raman spectroscopic evidence that are indicative of local structure formation in imidazolium-based ionic liquids. Low-frequency Raman spectra of C n mimX, where C n mim stands for 1-alkyl(C n H 2 n+1 )-3-methylimidazolium cation and X represents the anion, exhibit broad bands assignable to collective modes of local structures. Spatial distributions of coherent anti-Stokes Raman scattering (CARS) signals from C n mim[PF 6] are consistent with local structures whose size increases with increasing n. Picosecond Raman spectra of S 1 trans-stilbene as a "picosecond Raman thermometer" show microscopic thermal inhomogeneity ascribable to local structure formation in C 2mimTf 2N and C 4mimTf 2N. We also describe two novel phenomena that we believe are relevant to extraordinary nanoenvironments generated by local structures in a magnetic ionic liquid C 4mim[FeCl 4]. 相似文献
976.
Polyolefins containing 1,3‐disubstituted cyclopentane units in the main chain have been synthesized by 1,3‐polymerization of cyclopentene (PCP), cyclization polymerization of 1,5‐hexadiene (PHD), and ring‐opening metathesis polymerization of norbornene following hydrogenation of the unsaturated main chain (H‐PNB) with various transition metal catalysts. These polyolefins were applied to nucleating agents for isotactic polypropylene, and relationship between the structure of the polyolefins and nucleating effect was studied by DSC, polarized optical microscope, and WAXD. All the polyolefins had an effect of nucleation for isotactic polypropylene (PP). Of the polymeric nucleating agents, H‐PNB showed the most effective nucleation. Addition of PCP, which was obtained with a nickel catalyst with diimine ligand, to PP induced β‐modification. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2953–2958, 2006 相似文献
977.
The lipid and FA compositions of various organs and of the stomach contents of Scomber australasicus were analyzed. DHA was characteristically the major FA of all the major lipid classes of all organs except for liver TAG.
The mean DHA contents of the various organs accounted for more than 17% of the total FA (TFA), whereas those in the stomach
contents, originating from the prey, fluctuated and were generally low. In particular, the DHA levels in the TAG from all
organs of S. australasicus accounted for up to 17% of TFA, even though it is a neutral depot lipid. S. australasicus contained markedly high levels of DHA, even though it is a small-sized Scombridae species, and its high levels of DHA were
close to those in large-sized highly migratory tuna species. Furthermore, DHA levels in its muscle TAG were consistently high,
compared with those in the visceral TAG, which might be directly influenced by the prey lipids. These phenomena suggest that
long-distance migration has a close relationship with high accumulation of DHA in fish tissues, since S. australasicus is reported to migrate in offshore water, similar to highly migratory tuna species. Additionally, the physiological selective
accumulation of DHA in the muscle during migration is caused by in vivo metabolism of FA in the vascular system, suggesting that DHA is poorly used as a source of migration energy, though it is
provided abundantly through the prey lipids. 相似文献
978.
Controlled growth and shape formation of platinum nanoparticles and their electrochemical properties
Minoru Inaba Miwa Ando Akihiro Nomoto Koichi Matsuzawa Taro Kinumoto Zempachi Ogumi 《Electrochimica acta》2006,52(4):1632-1638
Cubic Pt nanoparticles were prepared from a solution of K2PtCl4 containing sodium polyacrylate as a capping reagent. The effects of the Pt/polymer molar ratio, the average molecular weight (Mw) of the polymer, and reaction temperature on the shape and size were investigated. When the polymer of Mw = 5100 was added at a molar ratio of Pt/polymer = 1/12, cubic platinum nanoparticles of an average size of 10.3 nm were predominantly formed (ca. 50% in number) at 25 °C. The electron diffraction pattern of the cubic nanoparticles revealed that they are single crystals with Pt {1 0 0} faces on the surface.The cubic nanoparticles were electrochemically active, and showed strong features of Pt {1 0 0} faces on cyclic voltammogram under argon atmosphere. After repeated potential cycling in the range 0.05-1.4 V, the features of Pt {1 0 0} were gradually lost, and changed to those of polycrystalline Pt. Rotating ring disk electrode measurements in O2-saturated H2SO4 solution revealed that the cubic nanoparticles had a high catalytic activity for oxygen reduction reaction (ORR). After polycrystallization by repeated potential cycling, the activity for ORR and hydrogen peroxide formation decreased slightly, which were attributed to the surface structural change from Pt {1 0 0} to polycrystalline. 相似文献
979.
Koichi Ito Koichi Satoh Moriaki Goya Tohru Yoshida 《International Journal of Mechanical Sciences》2000,42(11):2233
Theoretical prediction of forming limit strain of sheet metal is developed in the framework of the three-dimensional general bifurcation theory. The onset of the three-dimensional discontinuous velocity field in the biaxially stretched uniform sheet is predicted. Three fundamental mode vectors, i.e. shear horizontal, shear vertical and normal modes are introduced and it is demonstrated that any bifurcation mode is represented by the linear combination of them. The onset of the bifurcation is numerically analyzed in terms of the modes by the use of the linear comparison solid originally introduced by Hill in 1959. In this study, a linear constitutive relation is adopted for the linear comparison solid, which is developed based on the constitutive theory proposed by Goya and Ito and is capable of incorporating the directional dependence of the plastic strain rate on the stress rate. The numerical results show that forming limit strains predicted by the three-dimensional mode theory is much higher in general than that given by Stören and Rice in 1975. Then, it is revealed from the three-dimensional mode analysis that the bifurcation mode that arises can be changed from one type to another according to the sign of stress ratio. It is also shown that the strain limit predicted by the three-dimensional mode analysis gives upper limit lines for the bifurcation lines proposed in the past for any linear strain-path directions. 相似文献
980.
Characteristics of MnOy–ZrO2 and Pt–ZrO2–Al2O3 as reversible sorbents of NOx were investigated under dynamic changes in atmosphere. These sorbents can be used reversibly with a change of C3H8 concentration in the reaction gases. Catalytic reduction of NO occurred in the presence of propane, which was more pronounced on Pt–ZrO2–Al2O3 than on MnOy-ZrO2 due to high activity of Pt surface for this reaction on MnOy in MnOy–ZrO2. The sorption was observed as soon as the atmosphere changed from a reducing to an oxidizing one. This implies that a high equilibrium partial pressure of O2 is necessary for NO uptake since the sorbed NO−3 species becomes stable. The beginning of NOx desorption atmospheres was somewhat dependent on the amount of stored NOx. The presence of propane in the gas phase strongly affected the characteristic sorption and desorption properties of MnOy–ZrO2 and Pt–ZrO2–Al2O3. The sorption and desorption properties are different for MnOy–ZrO2 and Pt–ZrO2–Al2O3, since the noble metal or metal oxide possesses unique activity for the NO reaction with C3H8 and the amount of oxygen available for oxidative sorption of NO. 相似文献